Can someone explain why the US house of representatives seat share is so different from the presidential vote share?
eg in Ohio Obama got 50.1% but the Democrats won only 4 of 16 house seats?
I was under the impression the house seats were elected on a first past the post system from single seat constituencies / districts.
However if this is the case, and if party votes mirror the presidential vote, it's hard to see how the Democrats would get just 25% of seats.
I also understand there's a fair bit of gerrymandering in electoral districts, but surely that can't explain such a large effect?